The present invention relates to an azinphos-methyl powder insecticide composition characterized by an elevated deflagration temperature and a reduced tendency to undergo exothermic decomposition.
Insecticides are used in a variety of forms. One form useful for treating enclosed, limited spaces is as a fumigant. Japanese Patent 63039803, for example, teaches an insecticide fumigant which undergoes controlled decomposition. In this fumigant, the insecticide is mixed with a thermodecomposable compound that will produce nitrogen and carbon dioxide at temperatures less than 300.degree. C. Among the thermodecomposable compounds taught to be appropriate are ammonium salts, metal azides, inorganic carbonates and organic carboxylic acids. These thermodecomposable compounds are used in quantities such that they constitute at least 50% by weight of the fumigant mixture.
Insecticides for more open areas are generally applied by spraying. Sprays can be produced by either diluting liquid concentrates or by adding liquid to an insecticide in wettable powder form. The wettable powder forms are generally preferred because they are much easier to ship and store. The dry powder is also less likely to penetrate the clothing and skin of the person handling it than a liquid concentrate. It is also easier to clean up a powder than a liquid in the event of a spill. However, insecticides such as azinphos-methyl which are in powder form are sensitive to heat and as the temperature increases, an exothermic reaction occurs which could result in the deflagration of the powder.